Strip with fabric having exactly two layers of fabric

ABSTRACT

A belt, in particular a drive belt, is proposed having a woven fabric (G) as a traction layer, said fabric comprising two woven fabric layers, which are interlaced together. Both woven fabric layers have plain weaves. Such a belt transmits high tractive forces, while remaining flexible at the same time.

[0001] This invention relates to a belt comprising a woven fabric as a traction layer.

[0002] The term “belt” is used herein as a collective term for drive belts, conveyer belts and process belts.

[0003] The traction layer of a belt, and especially of a drive belt, frequently consists of one or more layers of a thermoplastic synthetic material or of one or more layers of a textile article, in particular of a woven fabric. This traction layer is rubber coated.

[0004] A traction layer made from thermoplastic synthetic material is made, for example, from an extruded polyamide sheet. Such a traction layer is characterised by high flexural strength and low compressive strength.

[0005] The threads of the textile articles and especially of the woven fabrics, can be made from synthetic raw materials, for example from polyamids, aramids, polyesters, polyolefins, etc. However, they can also be made from natural raw materials, for example from cotton, from stalk fibers such as flax or hemp, from wool, from silk etc. Moreover, mineral raw materials such as, for example, glass or carbon are a possibility for use as a raw material for the threads. Lastly, mixtures of all these raw materials come into consideration as well. The woven fabric can be produced from all known types of yarn, such as for example multifilaments, monofilaments, staple fiber yarns or folded or cabled yarns.

[0006] The traction layer of the belts, especially of the drive belts, is exposed to enormous stresses in operation. Traction layers composed of thermoplastic synthetic material are not very flexible (see above) and therefore require large rollers or pulleys to guide or deflect them, which entails a comparatively large consumption of drive energy (the mass of the rollers or pulleys has to be driven). In the case of traction layers composed of textile articles, in contrast, flexibility is high but at times the transmission of force is not sufficient, which is why plural such textile traction layers are frequently adhered together. This is disadvantageous in that this requires a further operation in manufacture, namely the adhering together of the textile traction layers. Furthermore, the material requirements increase as a result, since two or more textile traction layers are needed. However, above all, an impairment of the flexibility of the traction layer as a whole results.

[0007] This is where this invention seeks to provide a remedy. It is accordingly an object of this invention to propose a belt, in particular a drive belt, which not only permits a large transmission of force, but also remains flexible at the same time and if possible provides a suitable surface structure for the mechanical grip of the rubber coating.

[0008] This object is achieved by the belt characterized by the features of independent claim 1. Particularly advantageous embodiments are established by the features of the dependent claims.

[0009] To achieve good transmission of force and flexibility at the same time, the traction layer has a woven fabric, which comprises (a construction of) two layers, which are interlaced together. At least one of the woven fabric layers has a plain weave, a derived plain weave, a mixed plain weave or a satin weave. In this way it does not need a further production step to adhere together the layers. Finally, by this change in the technique to join together both of the fabric layers a ribbed-form surface structure arises, which improves the mechanical bond between the rubber coat and the woven fabric. Depending on which type of weave is applied, the rib can appear on one side or both sides of the woven fabric.

[0010] Further advantages are revealed in the subsequent description of embodiments aided by reference to the drawings, where

[0011] FIGS. 1-5 each show a weave repeat, with which the formation of a first embodiment of the woven fabric (FIG. 5) of a traction layer of a drive belt of this invention is apparent;

[0012] FIGS. 6-8 the embodiment of the weave repeat according to FIG. 5 together with a less idealized depiction of the corresponding woven fabric unit and a larger section from the corresponding woven fabric;

[0013] FIGS. 9-10 each show a weave repeat of further embodiments of the woven fabric of a traction layer of a drive belt of this invention; and

[0014] FIGS. 11-14 the embodiment of the weave repeat according to FIG. 5, together with further depictions of the same weave repeats (therefore of the same woven fabric).

[0015] FIGS. 1-5, which each show a weave repeat, should illustrate the formation of a first embodiment of a woven fabric of a traction layer of a belt of this invention, here in the form of a drive belt, as described below. A weave repeat is the smallest weave unit whose repetition forms the fabric. A weave diagram is a schematic depiction of the interlacing of horizontal weft threads and vertical warp threads. The crossing points are symbolized by small boxes (squares in the present case). A filled box or square indicates that the warp thread in question passes above the particular weft thread and a blank box or square indicates that the warp thread in question passes under the particular weft thread. A weave diagram can be used to depict either only one repeat, a plurality of whole repeats or one repeat and a plurality of parts of the repeat to indicate how the repeats join up. The figures more particularly described herein below each depict one weave repeat, which, however, may also be referred to as a weave diagram.

[0016] In FIG. 1 one can see the two woven fabric layers 1 and 2, which are depicted in the same weave diagram. The weaves of both layers are depicted in one plane. Therefore for layer 1 only the first and third column and the first and third row are relevant and for layer 2 only the second and fourth column and the second and fourth row are relevant. The numbering of the warp and weft threads begins in the bottom left corner of the weave repeat, or weave diagram.

[0017] The depiction in FIG. 1 denotes that in the first layer 1 the warp thread K1 passes under the weft thread S2, but over the weft thread S4. The situation is exactly the opposite for warp thread K3, it passes over the weft thread S2, but under the weft thread S4. In the second layer 2 the warp thread K2 passes over the weft thread S1, but under the weft thread S3, with warp thread K4 the situation is reversed, it passes under the weft thread S1 but over the weft thread S3. If both layers are viewed separately, it can be seen that each individual layer has a simple plain weave. In this case there are two weave repeats for each individual layer, multiples of this are also possible. There are four weave repeats for the whole weave diagram in this case, multiples of this are also possible.

[0018] In FIG. 2, layer 2 is defined as the upper of the two layers through further passes of the warp threads K2 and K4 over the weft threads S2 and S4 (with broken line-filled squares). This is also included in the weave diagram in FIG. 3. In this construction stage both layers are not yet interlinked.

[0019] In FIG. 4, to mark the position at which both layers 1 and 2 should be interlinked, a cross V1, V2 is placed in the appropriate square. The interlink is carried out in such a way, that at one position, e.g. in the square, corresponding to the first column and the third row of the weave diagram (cross V1), the warp thread K1 of the “bottom” layer is over the weft thread S3 of the “upper” layer; whereas in the square, corresponding to the fourth column and the second row (cross V2), the warp thread K4 of the “upper” layer runs under the weft thread S2 of the “bottom” layer (first layer). In this manner both layers are interlinked and result in a woven fabric, the weave repeat or weave diagram P1 (diagram with a single repeat) of which is depicted as a whole in FIG. 5. The different depiction of both layers in FIGS. 1-5 aids simply in the explanation of the construction of the woven fabric.

[0020] The depiction in FIG. 5 denotes therefore that the warp thread K1 passes under the weft threads S1 and S2, but over the weft threads S3 and S4. The warp thread K2 passes over weft threads S1 and S2, under the weft thread S3 and again over the weft thread S4. The warp thread K3 passes under the weft thread S1, over the weft thread S2 and under the weft threads S3 and S4. The warp thread K4 finally runs under the weft threads S1 and S2 and over the weft threads S3 and S4.

[0021] The linking of both woven fabric layers is therefore chosen so that the alternating threads between the woven fabric layers bind both layers together as strong as possible and at the same time form a transverse rib.

[0022] The weave diagram P1 in FIG. 5, whose construction is explained by FIGS. 1-5, is once again repeated in FIG. 6 to facilitate the comparison of the “technical” weave diagram with a less idealised depiction of the thread crossovers in FIG. 7 and FIG. 8. For the sake of simplicity the threads of the two layers are again differently depicted. As is able to be seen from FIG. 7, the warp thread K1 is under the weft threads S1 and S2, but over the weft threads S3 and S4, exactly as presented in weave diagram P1 (FIG. 6) with the aid of the filled out and empty squares. All other threads cross over each other according to the schematic depiction in the weave diagram P1.

[0023] In FIG. 8 a larger section from the corresponding woven fabric G is presented, in which the weave repeat P1 repeats itself within the woven fabric G. So that the pattern of the weave diagram P1 can be found again, the warp threads K1, K2, K3, K4 and the weft threads S1, S2, S3, S4 are correspondingly named.

[0024] Further embodiments of woven fabrics are presented in FIG. 9 and FIG. 10, in the form of the respective weave repeat or weave diagram P2 and P3, which are able to be utilized in the belt of this invention, in particular for a drive belt. The embodiments according to the weave diagrams P4-P6 (FIGS. 12 to 14) are only different depictions of the already described weave diagram P1, which for the sake of clarity is once again presented in FIG. 11.

[0025] Therefore for example the depicted form of the weave repeat or the weave diagram P4 according to FIG. 12 is the “negative” of the weave diagram P1 from FIG. 11. As far as the woven fabric itself is concerned, it means that one looks at the woven fabric from the other side (one looks therefore at the “reverse” side of the woven fabric). The woven fabric itself however remains the same.

[0026] From the depiction of the weave repeat or the weave diagram P4 from FIG. 12 one comes to the depiction of the weave repeat or the weave diagram P5 from FIG. 13, by virtually turning over the weave diagram P4 around its lower edge. The depiction of the weave repeat or the weave diagram P6 according to FIG. 14 corresponds to the “negative” of the weave repeat or the weave diagram from FIG. 13.

[0027] In principle therefore, at least one woven fabric layer has a plain weave, a derived plain weave (for example Panama, Reps etc), a mixed plain weave, and a mixed derived plain weave, or a satin weave. The second woven fabric layer can either be formed in the same manner as the first woven fabric layer or it can be formed differently to the first woven fabric layer, so that can result in the fact that both woven fabric layer sides have the same or different surface structures.

[0028] Furthermore, the woven fabric may contain conductive threads, which is particularly advantageous since drive belts—in order to ensure driving—and other belts always generate friction on the surface of a drive element (e.g. a metal pulley). An electrostatic charge can build up in this manner. At the separation point of the rubbing bodies—for example where the drive belt loses contact with the pulley—a spark discharge can then occur. Electrically conductive fibers can then prevent the occurrence of this sparking by, for example, carrying the charge to a spot where the drive belt is in contact with an electrically earthed structural component or surface (e.g. on the metal pulley), so that the charge is lead away without the formation of a spark.

[0029] The warp threads and the weft threads used may be yarns that may be constructed as continuous filament yarns (monofilaments, multifilaments) or which may also be staple fiber yarns or folded or cabled yarns (folded yarns are two yarns twisted together, cabled yarns are several folded yarns twisted together).

[0030] Yarn linear density may vary as a function of the number of threads per centimeter in the range from about 3 tex to about 300 tex not only for the warp threads but also for the weft threads.

[0031] The thread count can vary as a function of yarn linear density in the range from about 4 threads/cm to about 4000 threads/cm not only in the warp direction but also in the weft direction. The woven fabric may have the same or else different thread counts in the warp and weft directions.

[0032] Possible fiber base materials include not only natural base materials such as, for example, cotton, stalk fibers (e.g., flax, hemp), wool, silk and also ramie etc., but also synthetic base materials such as for example, polyesters, polyamids, polyolefins, aramids, etc., as well as mineral base materials such as, for example glass and carbon etc., and also mixtures thereof. 

1. Drive belt having as a traction layer a woven fabric (G), which comprises exactly two layers of woven fabric (1,2), which are interlaced together, characterized in that at least one of the woven fabric layers (1,2) has a plain weave, a derived plain weave, a mixed plain weave or a satin weave.
 2. Drive belt according to claim 1, wherein the other woven fabric layer (2,1) has the same type of weave.
 3. Drive belt according to claim 1, wherein the other woven fabric layer (2,1) has another type of weave.
 4. Drive belt according to any one of claims 1 to 3, wherein the smallest weave unit (P1) of the woven fabric is constructed according to the pattern shown in FIG. 11 of the drawings, where the columns each represent the warp threads (K1, K2, K3, K4) and the rows each represent the weft threads (S1, S2, S3, S4), and where in the columns alternately a warp thread (K1, K3) of one layer (1) is arranged next to a warp thread (K2, K4) of the other layer (2) and where in each of the rows a weft thread (S1, S3) of one layer (1) is arranged next to a weft thread (S2, S4) of the other layer (2), and where a dark field in this pattern denotes that the warp thread passes over the weft thread and where a light coloured field in this pattern denotes that the warp thread passes under the weft thread.
 5. Drive belt according to any one of claims 1 to 3, wherein the smallest weave unit (P2) of the woven fabric is constructed according to the pattern shown in FIG. 9 of the drawings, wherein the columns each represent the warp threads (K1, K2, K3, K4) and the rows each represent the weft threads (S1, S2, S3, S4) and where in the columns alternately a warp thread (K1, K3) of one layer (1) is arranged next to a warp thread (K2, K4) of other layer (2) and where in each of the rows a weft thread (S1, S3) of one layer (1) is arranged next to a weft thread (S2, S4) of the other layer (2), and where a dark field in this pattern denotes that the warp thread passes over the weft thread and where a light coloured field in this pattern denotes that the warp thread passes under the weft thread.
 6. Drive belt according to any one of claims 1 to 3, wherein the smallest weave unit (P3) of the woven fabric is constructed according to the pattern shown in FIG. 10 of the drawings, wherein the columns each represent the warp threads (K1, K2, K3, K4) and the rows each represent the weft threads (S1, S2, S3, S4) and where in the columns alternately a warp thread (K1, K3) of one layer (1) is arranged next to a warp thread (K2, K4) of the other layer (2) and where in each of the rows a weft thread (S1, S3) of one layer (1) is arranged next to a weft thread (S2, S4) of the other layer (2), and where a dark field in this pattern denotes that the warp thread passes over the weft thread and where a light coloured field in this pattern denotes that the warp thread passes under the weft thread.
 7. Drive belt according to any one of claims 1 to 6, wherein the woven fabric (G) contains electrically conducting fibers. 